Actually, it's probably more likely to be the legacy of all the NW flights from Asia coming in. As a veteran of those flights, you would be amazed at what Asians try to bring in--in particular, prohibited food and agricultural products. On just about every incoming flight, Customs inspections were producing a bounty of no-no's. I suspect that far outweighs instances of finding contraband coming from AMS. ;-)

Customs does have the right to check out your passport and often are looking for confirmation of where you went (which should match the line you filled in your Declaration form)...maybe in some cases, for travel "patterns". In past years, I've been approached in the baggage claim area (while waiting for luggage to appear) by roving agents who check passport and declaration, then make a mark on the form and tell you when luggage is in hand, to either go to the exit line or the inspection lines. So I guess you could call this "Customs profiling" which I don't have a problem with, as it's the sensible approach.

This year, Global Entry has been great at speeding up/streamlining the entire US entry process--though so far, I have not received an X receipt from the kiosk that would force an inspection stop rather than a quick dash for the exit.